With image capturing apparatuses such as a digital camera, semiconductor memory cards are widely used as storage media for storing captured image data. When transferring the stored image data to an external apparatus such as a personal computer (PC), a printer, or a television receiver (TV), conventionally a digital interface of the digital camera is generally connected to a digital interface of the external apparatus with a cable. See, for example, Japanese Patent Laid-Open No. 2005-223710.
Also, in recent years, a combo card is known that has, in addition to a memory function for storing image data, a wireless communication function. By mounting this combo card for use in a digital camera, it is possible to wirelessly transfer image data from the digital camera to an external apparatus that has a wireless communication function.
The digital camera can switch the memory function and the wireless communication function of the combo card between being activated and deactivated. When the memory function is active, the combo card operates in response to reception of a command from the digital camera. Therefore, the digital camera only needs to supply a clock to the combo card when actually accessing the combo card to read or write image data and the like. On the other hand, when the wireless communication function is active, the combo card first issues an interrupt signal or the like to the digital camera that serves as a host. Accordingly, the digital camera needs to constantly maintain the state in which communication with the combo card is possible so as to be able to receive signals from the combo card any time. Therefore, the digital camera continues to supply the clock as well as supplying power to the combo card even while no communication is actually being performed.
As a communication protocol for use in wireless communication between the digital camera and the external apparatus, for example, Picture Transfer Protocol (PTP), which is defined by the Still Imaging Device Class of the USB standard, is known. Also, the Digital Living Network Alliance (DLNA) is known. The former is often used for wireless communication with, for example, a PC, and the latter is often used for wireless communication with, for example, an AV device such as a TV.
In order to wirelessly communicate with an external apparatus using the wireless communication function of the combo card, the digital camera needs to use a communication protocol with which this external apparatus is compatible. On the other hand, the combo card is not necessarily compatible with all communication protocols, and the compatible communication protocol varies among combo cards.
Accordingly, in order to wirelessly communicate with an external apparatus, the digital camera needs to identify the communication protocol with which the combo card is compatible and to select, as the communication partner, an external apparatus that is compatible with this communication protocol. For example, in the case where the combo card is compatible with PTP but not DLNA, the digital camera can select, as the communication partner, a PC that is compatible with PTP but not a TV that is not compatible with PTP.
In order to identify the communication protocol with which the combo card is compatible, the digital camera needs to activate the wireless communication function of the combo card and then to query the combo card.
However, as described above, once the wireless communication function is activated, clock supply and the like is performed even while no communication is actually being performed, thus resulting in the power of the digital camera being wasted. On the other hand, if the wireless communication function is not activated until the time at which communication is actually performed, the digital camera cannot identify the communication protocol with which the combo card is compatible. As a result, the digital camera cannot appropriately select, as the communication partner, an external apparatus that is compatible with the same communication protocol as that of the combo card.